Concrete tamping device



Aug. 19, 1952 B P|ERRE 2,607,569

CONCRETE TAMPING DEVICE I Filed July 2, 1946 2 SHEETS-SHEET 1 Fig.2 Fig.5

(B ,B F /erre WWMJQZM fifforng s Aug. 19, 1952 P|ERRE 2,607,569

CONCRETE TAMPING DEVICE Filed July 2, 1946 2 SHEETS-SHEET? al mag; fad 5 M fiffor gys Patented Aug. 19, 1952 urrah STATES PATENT olii? 1613f v If e n a ny 2, 1946, Serial No. 681,098 7 2' In France March 16, 1944 I V :se'aion- 1, Public Law 690, August 8, 1946 A known way of compacting concrete is to plunge into it the end of a needle maintained in vibration. r I T Compacting devices operating in this way fall into two main classes according to the sort of vibration communicated in the needle.

(1) In the first class, vibration of the needle is caused by thevibrator (which may be of known type, for example a form'vibrator) fixed to the end of the needle protruding'from the concrete.

The vibrator impressesa' rapid'oscillatory motion on the point to which it is fixed; and the amplitude of the movement transmitted to different points in the concrete is greater or less according 'to the mass of the'needle handle, according the flexibility of "the needle, and according to the depth of penetration of the needle into the concrete. Thefcon'c'reteiscompacted more or less satisfactorily butsomewhatirregularly,

(2) In'the second class, vibration of the needle is caused by an eccentric mass rotating within the needle itself around the longitudinal axis of the needle. As a rule good results are obtained withsuch a" needle because the amplitude of the vibrations transmitted to the concrete is sensibly constant throughout the length of the needle.

But such a needle cannot-be used to compact concrete when the concrete is formed in layers (whether vertical or horizontal) of less than 50 mm. thickness,'as is the'ca'se; notably, in the narrow joints of masonry, and in reinforced concrete with closely spaced reinforcements.

Ihei present invention enables better results to beachieved in all cases than .with known devices of the first class at least as good results are obtained as with known devices 'of'thesecond class in thicknesses of- 'concrete'gre'ater'than' 45 mm. and' also very good' resiilts areo'btai'n'ed in lesser thicknesses. 1

t Accordingto the invention these results are obtained by the use of a needle of non-circular section to which is given an alternating movement .of rotation; that is to say an oscillation around its longitudinal axis.

In. order that all points on the needle may impress equal. movement of the designed magnitude upon' the concrete in'contactwi'th the needle, whatever the distanceof these pointsfrom the axis of oscillation,'the sectionof the; needle by a plane atright anglesto theaxisi of oscillation may with advantage be given the form of a portion of the curve described in polar co-ordinatesby theequation The origin o is at t e centreof loscillation, The radiusvector makes an a ngle with the ttor a e Qt; I

Patent expires March 16, 1964 4 Claims. (01. 259 1) m is the shortest vector at which the'oscillation gives the designed displacement to the concrete,

Any means may be employed to impartoscillation to the needle.

Generally speaking the needle will, be subjected to an alternating couple about its longitudinal axis. I i

Preferably the needle 'is made fast to a part subjected to the action of forces alternating in sense, the directions of which lie both in a plane perpendicular to the longitudinal axis of the needle and in planes sensibly parallel to the axis and symmetrical with respect to it, so that they transmit to the needle atorque alternating in sense. v.

In a first construction, two shafts turn at the same speed but in opposite directions carry eccentric masses which when they are in the plane containing the shafts and the longitudinal axis of the needle are symmetrical with respect to the longitudinal axis of the needle.

These shafts may be parallel to the longitudinal axis of the needle or they may be co-axial and at right angles to-it and carry masses at each of their extremities, the masses on the ends next to the longitudinal axis of the needle being displaced by from the masses'at the ends distant from the axis. 1 i 3 I In a second constructionaccording tothe invention the needle is made 'fast to a member in which are two cylinders containing double-acting pistons operated by fluid pressure, the axes of the cylindersbeing at right'a'ngles to the longitudinal axis of the needle and symmetrical with respect to it, the pressure fluid driving the pistons in opposite senses so that the forces produced by their simultaneous displacements produce a couple the axis of which is that of the needle.

By way of example there are shown in the accompanying drawings: z

In Figure 1 part of the curve above described as the preferred form of the section of the needle; I I

In Figures 2 to 5 four cross-sections of needles are shown according to the present invention; each cross-section in each-figure is shown in two positions, one position is shown in full lines and the other position is shown in dottedlines;

In Figure 6 a view of one construction of the invention partly in section,

In Figure 'Zja section on the line VII-VII ofFigure6," k In Figure 8 a sectionof part ofa second construction of the invention; I

In Figure 9 a view from above of the construction shown in Figure 8 the topjofthe casing beingremoved, s a

In Figure. 10 another construction of the in-' vention;

from it; 7 1

Figures 2-5 illustrate various cross-sections of aeo zcec in dotted lines represents the curve shown in full,

lines after rotation through an angle V t o and is a curve parallel to the latter and distant the needle which is a feature of the invention.

The non-circular sections of Figures 2-5 are oc-' cillated about the longitudinal-axis of the needle, and, these sections correspond. to the form of the foregoing equation to describe the curve, the foregoing equation expressed in polar coordinates. Each of the cross-sections illustrated in Figures 2-5 iindicate two positions forthese cross-sections; one of these positions being shown in a full line, the other in dotted line.

In the device shown in Figures 6 and .7 a mo tor 2! drives through a flexible transmission 22 a shaft 23. on which is secured a bevel pinionZA.

The bevel pinion 2.4 drives through similar pinions 25; and 26 two. shafts 21- and 2.8 to which it. transmitsv rapid movements of rotation of the same-speed and of opposite sense.

Upon the shaft 21 are securely fastened two equal masses 2,3 and 30, arrangedsymmetrically with respect to. a. point on the shaft .21 equidistant fromthe point at which the masses 29 and 39- are fixed. Shaftifi and its masses, 3| and 32 are identical with the shaftv 21. and its masses 29 and 35. At the beginning of the movement the four masses are inj the plane containing the longitudinalaxis f the ne dlev and e axes of the shafts 21 and 258 the. masses 3i! and 3! being on the side of: theshaf stowards. the n e e p i t. and the ma ses, Z9 an 3.2 ion t e S de ow d the flexible transmission. The shafts 23, 21. and 28, the bevel pinions 24, 25 andliand the masses 3.0 and 3 eree z oeecl. n a casing 3 which arebear psfer he h eesheft r Upo thi a in are mounte a e e 3 v and ne dle 35 :eo-ex el; it t eh nd e and o o eaient shapa orine ence of. he. sec io show i F sure. hi need e is ob p un into the n e e.

n. conse uenc o he r d. rotation t masses 23 32 when they are in the position shown in Figure 'Lcreate by their centrifugal forces a couple of which the axis is :r-m'. while the masses 3!) and 3| create a much smaller'o'pposite couple, so that there is a resultant tending to turn the casing about the aids :ic-.ac when the masses are in the position shown in Figure 6 their centrifugal forces produce no cou ple about the axis far-22.

So on each revolution of the shafts '2'! and 23 the casing makes an oscillation about 'the'axis :c-m carrying with it the needle 35 which is securely fixed to it.

The needle 35 is made, as indicatedin Figure 5, of a light metal casting comprising curved elements of the'form above described, so designed that the displacement of the needle siirfa'ce in contact with the concrete has nearly everywhere the desired value. j

In theconstruction shownjin Figures 8 and 9 the shafts 36 and'3'l, instead of being at ri ht angles to the longitudinal axis :r-m' of the needle 35 are parallel to it and each carries two masses 38. These are eccentric to the shafts 33 and 31 4 and are so placed that when they are in th plane'containing the shafts '36- and 31 and the axis ar-x they are symmetricalwith respect to the axis x-m. Motion is transmitted to the shaft .315 from an exterior source of 'movement as in Figure 6 and on shaft 34 is keyed a pinion 39 engaging with identical pinions 40 and 4| keyed upon the respective shafts 36 and 31. The whole construction is arranged in a casing 42 like that shown in Figure 6 and to this casing is secured the needle 35 in manner analogous to that described below in connection with Figure 10.

The working of this arrangement is substantially analogous to that of the construction shown inFiguresfiandT. .5 1 1 I In the constructioni shown ln ,-Figures 15 and 11 the needle 35, of such a shape ashafsi been mentioned above, is seouredito. a socket 5| of a truncated pvramidform whieh fits upon a boss 52 of similar polygonalisection, and is firmly pressed upon the bossjby. two scr ws 53. and 54. The boss 52 ispart ofa casing 55; secured to a hollow handle 56 to which is joined a. flexible compressed-air conduit 5-1.;

In the casing 55 areformedtwo cylinders 58 and :59 in'whioh moveheavy p stons 6.1 and. 62- The cylinders lie in aplane perpendicular to the lon itudinal axles-extorthe needle. 35,. and are symmetrical with respect tothat axis. Thepistons GI and eziare moved yeompressed airsupplied through thejcon'duitil and'a passa e 63,;

In Fig. 11,'piston.s 6,! and 62 located incylinders 53 and 59 respectively, are reciprocatmgly moved by compressed air admitted through p'as sage or groove 63 in. cylinder .59, upper passage or groove '65 in casing. 55., passage or roove 6'! andconduit or passage 6.8 to. enter into chain ber '69:. Compressed air is likewise admitted via. passage or conduit '66. in --piston Bl into "chamber l9. Air in the upper part-of chamber 10 is vented through port'Ha. Also, passages 16 in chamber 39 and lower passage -l;'l=i;n casing 55 at tlmes'communicates with passage. or'g'roove H, in cylinder 53 and with passage. 15 and port Ilia; Passage or groove 19, in cylinder 59; corresponds to pas sage 14incylinder58 1:5

When-one of thepistons GI. and 5-2 is moving in the. direction'indicated by'the arrjow-f the other is moving in the'opposite direction. The blade 35 is therefore subjected to, apalte-rnatin movement around its-longitudinalaxis; J'

The simultaneous movement .of the pistons 6;! and 62 may be obtained? for .examplaiby' making the piston 6| serve as a slide valve controlling the supply of compressed air to and its exhaust from-thecylinder5fl; "1' -5 In the construction illustrated; whenit: in the position shown in l1, alirsupplied by the conduit 63 is led 'tliroligh thefgrobve 64 through the passagewayfi5inipiston Blbothj'to the conduit 66. in piston Bdrandto:thegroove'fili and conduit 6'8'o'f piston :62; and so tothe'chambers 69. and 10 in cylindersiflrand 5.9." i

With the pistonsin' Tthe positionshown 1 1' pressure air i'sadmittedrvia' passages'til; 65.; 6:1

and 68 to chamber fifl andalso passage (ity to chamber 10. Pistons 61 iand '62 now moveto their opposite positions, air in the upperp'artof chamber 10 venting via port 'Tla and the air in the lower part/0f chamber 69; venting via passages 16, lower passage H in casing 55, passages. 14 and 15 and port 1m.

On reverse; operatic seawater a. .Q. misc ef passages 19 and 16 to thelowenpartof chamber sbf the n e le. andjth y m ke" 89 and also to. passage 15.110 upper part of ,chamr berg,'l0.- Air 7 in the other ends of chambers 69 and :10 vent, via-passages 68, 61, ventHa espectively;

Consequently the pistons 55 '66,, Hand are vigorously When it reaches endof itsi cyl-inder ton 6| uncovers the port 11 through which the compressed air exhausts. The-groove 64 is now no longer in register with the admission port 12, but the groove "l4 registers with the opening of passageway 15, and the pistons Gland 62 are given an opposite movement and create a couple ofoppositesign. I v 1 v With the invention disclosed hereimthere'is secured equal displacements of the concrete in contact with the needle whereby a regular tamping of the concrete is secured. The followin calculation shows that the result sought issecured. V1 f,

'- Calculation l Assume the curve (0) is defined by polar coordinates by the equation:

1 l r Y ta- ,-M -e where r designates the length of'the radius vector of a point of the curve and efthe' angle ofthis radius vector with the axis o'x'or origin. 1

We will demonstrate that by rotating this curve (Co) a small angle a about the origin 0, there is obtained a new curve (C1) for which, for all points wherein r ru', the distance from the curve (C0) is constant and equal to aTo.

placed in opposite senses. Theforces resulting V After a rotation through an angle a about ,0, the point A0 arrives at A1 upon the curve C1. Drop from A1 a perpendicular A1B upon the tangent A03 to the curve Co at the point A0. The angle a being small, the length A1B represents by the second order almost the distanceof a point from the curve (C1)' to the curve (Co).

Let us represent the length A1B by X. We have: I

( X =AQA1 co B=ra cos B where c designates the angle AOAIB.

Let us now determine the angle ,8 by calculus from the curve 0 about the point An.

An increment no ofthe angle 0 corresponds to an increment Ar of the radius vector.

In the right angular triangle AoCD we have:

and at the limit when 0 approaches 0 Y'l a 4 v v Qiit o rh hd. h 'ans es C A B e equal as they have their sides respectively per- Let us reckon rdo/dr starting from the equation of the curve Co:

We have:

and

Transfer"this value-into Equation 3 above:

from which X=aro upon the evident condition as has been set forth above that 7' 7o and this regardless of what may be the value of r, which was to be shown.

Naturally the invention is not limited to the examples described.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claimis: v I

1. Apparatus for tamping concrete and analogous material comprising aneedle introduced into the mass to be tamped, a vibrator comprising two cylinders whose;axesjare;parallel to one another and perpendicular to the longitudinal axis of said needle and symmetrical with relation to said longitudinal axis, two pistons located in said cylinders; fiuidoperated means for op erating said pistons inopposi te directions, a body fixedto said cylinders and said needle'and transmitting the vibrations of -'thevibratorto-saidneedle fl v I 2. A21 apparatus asset forth in claim 1 in which one of said pistons serves as a distribution slide-valve for saidfiuid operated means for the otheipi'ston' I apparatiisas styfo'rth in claim 1 in which the section of said {needle through-a plane perpendicular 'to its longitudinalaxis constituted at least in part of portions of a curvature described in polarfcoordinates by the equation where the origin 0 of the cd-ordinates is at the longitudinal axis of the needle, the radius vector 1- makes an angle 0 with the axis ofjco-rordinates Or and To is the shortest radius vector at which 'alternati g rotationfgives the described displacementoif the concrete: 7 r V 4. In a tool for compacting concrete or like materials, a needle insertable in the mass to be compacted, said needle having a cross section formed at least in part of portions of the curve described in polar co-ordinatesby the equation where the origin 0 of the co-ordinates is at the longitudinal axis of the needle, the radius vector r makes an angle 0 with the axis of co-ordinates 0a: and Wis theshortest'radius vector at which alternating rotation gives the described displace ment of the concrete.

nitNARD PIERRE. p f f; REF nENens-mfin The following r'eferenesare'of record in the file of this patentf UNITED STATES PATENTS Number Name Date 1,221,038 Earle Apr. 3, 1917 1,875,622 Lockwood Sept. 6, 1932 1,911,966 Pickop May 30, 1933 2,020,374 Pickop "1,; Nov. 12, 1935 2,075,093 Cannon Mar. 30, 1937 

